Alarm bell



Dec. 16, 1947.

A. w. FRUH ALARM BELL Filed June 23, 1944 2 Sheets-Sheet l A w, F RUH ALARM BELL DEC. 1

Filed J1me 1944 2 Sheets-Sheet 2 Patented Dec. 16, 1947 UNITED STATES PATENT OFFICE ALARM BELL.

Arthur W-rFruli, Chicagmlll;

Application J ime 23-; 1944,.Seriall N; 541,676

(Cl. 1721-126X 8 Glaimsr. 1

This invention: relates to alarm bells, and more particularly it. relates to that type of alarm bellsa usedinzburglar orifirealarm systems.- A-mongits objects is to simplify and otherwise improve upon the construction of bells of this character. An-

other'object is to provide a solenoid for operating" the striker head and 'ha'ving'an armature guided by narrow non-metallic guide members whereby to minimize the friction between the armature armature whereby the length of the armature strok'em ay be varied. Anotherobject is'the' provision o'fmeans for supporting domes of several different diameters in proper position relative to the'striker head.

With these and other objects and advanta'ges in view, this invention consists in the several novel features hereinafter fully' set forth and claimed.

The invention is clearly illustrated in the drawings accompanying this specification, in which:

Fig. 1 is a front elevation of an alarm bell embodying one form of the invention, with the dome removed and illustrated in dotted lines;

Fig. 2 is a view partly in sideelevation and partly in vertical section taken substantially along the line" 2-2 of Fig. 1; and

Fig. 3'is' a central vertical section of. a fragment of a certain dome supporting post, an adapter and a dome of greater diameter, a fragment of. the solenoid being illustrated in side elevation.

Referring to said drawings, the reference character designates a base plate formed with obliquely extending arms 6, 1, having screw holes therein for receiving the bolts 0r screws that fasten the device upon its support. Mounted on the base plate is a solenoid. 8, the windingsll of which are contained in a metal cup-like shell In which is'provid'ed with wings l"l that are fastened to the b-aseplate as by screws [2. The end wall or head. i3 of the shell closes oneend thereof and a disc. l4 closes the oppositev end which is peened over the edge of the disc. As usual, a fiber jacket l5 encloses the. windings of the solenoid and a metal tube lfiis secured in the end wall l3 and disc M as by a press fit and provides the opening for receiving the armature l1.

Spaced from one end of the solenoid is a post 18' which is mounted upon. the baseplate and provides means to support the dome. Ill. The armature,v to all intents and purposes}. is: iii-floating armature; it. is guided to move in a-v right line Another direction by two: non-metallic. guide members: 2.0,, 21 preferably composed of.Bakehte. Theguide member 20- isinthe: form, of a;v bushingheld .in the; tube. [6: by press fit and the guidemember 2 I, may. berinthe form of ablocksecuredto the post. l8: asby screwsr22 Secured to oneend of. thearmatureis a. striker: head 23 which strikes the dome in sounding anv alarm. The striker head; maybe: formed; withz-a;

screw threadedneck 2.4.threadedly secured in; a? threaded bore. which extends in. fromv the adja-- cent. end ofthearmature. The striker. heade-x tends out. through the. hole: in the guide member 2i]. and. normally is spaced: a; short'distance away from the skirt. portion; of. the dome. Threadedly secured in. a threaded bore. in. the. opposite end: of. the armature is a, stemor rod 25. which extends. through a hole Isa in the post and is guided. in.

an aperture in the guide member H. A look nut 26. is threaded upon the stem 25 and bears against a washer 21 interposed between. the adjacent. end.

of the armature and the lock nut. Alight, coiledv compression spring 28 is interposed between the:

washer 2.1 and the disc I4 of the. solenoid and.

urges the armature in a direction opposite'to that;

" ated by a resilient blade. 33 fastened at one end upon one arm 34 of: the bracket 3.! as; by'screws 35. The blade extends along one face of the microswitch and when in its normal" position it.

depresses the pin 36, thereby opening the circuit through. the switch. The other end of the blade is held in the forked arm 31 of an angle bracket 38 which is fastened to the baseplate bymeans such as a. screw 39. which extendsthrough a slot 40 in the angle bracket; thus permitting of adjustment of the angle bracket toward'and awayfromthe other support of the blade. A block 4! of rubber or other resilient composition is fastened. upon the end of the blade and bears against the bracket;

The stem 25 extends through an aperture in the blade and is provided with a. shoulder such as a flex it in adirection awayfrom the switch when 3 the solenoid is energized. A set nut 43 may be threaded upon the stem and screwed up against the nut 42 whereby to lock the nut in fixed position upon the stem.

The domes for alarm bells of the present character are usually made in a number of standard sizes, and means are provided for supportin domes of three standard sizes in proper relation to the striker head. In the drawings I have shown an eight inch dome l9, a ten inch dome 19a and a twelve inch dome I9b, together with means to support and properly locate each dome in relation to the striker head.

On the end of the post 18 is removably secured an arm 44 to the free end of which is secured a washer-like spacer 45 which positions the dome relative to the striking head. A bolt 46 threadedly secured in the arm 44 fastens the dome on its support. A pin 41 secured in the spacer extends through a hole in the dome and positively prevents rotation thereof and, if desired, a washer may be interposed between the head of the bolt and the dome. In the end of the post I8 is secured a pin 48 which extends through either of two diametrically opposite holes 49 in the arm 44. A bolt 50 threadedly secured in the post fastens the arm in place thereon and the pin 48 definitely locates the arm in either of its two dome supporting positions. In Fig. 2 the arm 44 is shown in full lines as occupying the position for supporting an eight inch dome 19. For supporting a twelve inch dome 19b the bolt 50 is unscrewed, the arm 44 is disengaged from the pin 48 and turned around 180 degrees, bringing it into the position illustrated in dotted lines in Fig. 2 and the bolt 50 is then screwed back in place. A twelve inch dome may now be bolted to the arm 44 and its spacer 45.

For supporting a ten inch dome 49a, a separate adapter is provided, as seen in Fig. 3, which is interposed between the post and dome !9a and the latter is bolted to the post by a bolt 52. R0- tation of the dome is positively prevented by a pin 53 which extends through registering holes in the post, adapter and dome. Desirably a washer 54 is interposed between the head of the bolt 52 and the dome.

Electrical conductors 55, 56 lead through the circuit closers of the alarm system in which the alarm bell is used, one conductor running to a binding post 51 of the microswitch and the other conductor running to one terminal of the solenoid winding, the other terminal of the winding being connected by an electrical conductor 58 with another binding post 59 of the microswitch.

In the operation of the alarm bell above described, when the electric circuit is closed through the microswitch, the solenoid is energized and the armature is propelled toward the dome with the striker head striking the same. In its movement toward the dome the nut 42 on the stem 25 flexes the blade 33 in a direction away from the pin 36, thereby permitting the pin to be urged outward from the switch case and opening the circuit through the microswitch, whereupon the spring 28 retracts the armature, and as a result the stem 25 and nut 42 are moved back releasing the flexed blade which immediately straightens out, depresses the pin 35 and again closes the circuit through the microswitch thereby repeating the same operation and sounding the alarm until the circuit is opened at some place in the system.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence, I do not wish to be understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described or uses mentioned.

What I claim as new and desire to secure by Letters Patent is:

1. In an alarm bell, the combination of a base plate, a solenoid mounted on said base plate and having an armature guided therein for movement axially thereof, a switch in series with said solenoid mounted on said base plate, said switch having an actuating pin, a resilient switch actuating blade mounted at both of its ends on said base plate and arranged to engage said actuating pin, and a stem secured to said armature and. having a shoulder thereon for engaging said blade.

2. In an alarm bell, the combination of a base plate, a solenoid mounted thereon and having a shell for enclosing its windings, a dome supporting post mounted on said base plate, Bakelite guide means having aligned apertures therein, one guide means being secured in the shell of the solenoid and one secured on said post, and an armature guided for movement axially of said solenoid by said guide means.

3. In an alarm bell, the combination of a base plate, a solenoid mounted thereon and having a shell for enclosing the windings thereof, a switch in series with said solenoid mounted on said base plate, a dome supporting post mounted on said base plate, a Bakelite guide bushing secured in said shell and a Bakelite guide block secured on said post and having an aperture therein coaxially aligned with said bushing, and an armature having a striker head secured on one end and a switch blade actuating stem on the other end with blade engaging means adjustably mounted thereon, said striker head and stem being guided in said bushing and block respectively.

4. In an alarm bell, the combination of a base plate, a solenoid mounted thereon and having a shell for enclosing the windings thereof, a post mounted on said base plate, a Bakelite guide bushing secured in said shell and a Bakelite guide block secured on said post and having an aperture therein coaxially aligned with said bushing, and an armature having a striker head secured on one end and a switch blade actuating stem on the other end, said striker head and stem being guided in said bushing and block respectively.

5. In an alarm bell, the combination of a base plate, a dome supporting post mounted thereon, a solenoid mounted on said base plate and having an armature guided therein for movement axially thereof, and a blade actuating stem on its other end with blade engaging means adjustably mounted thereon, a bracket mounted on said base plate, a microswitch carried by said bracket, a resilient blade, one end of which is carried by said bracket and engaging a switch actuating pin, a second bracket mounted on the base plate for holding the other end of the blade, said switch being electrically connected in series with the windings of the solenoid.

6. In an alarm bell, the combination of a base plate, a dome supporting post mounted thereon, a solenoid mounted on said base plate and having an armature guided therein for movement axially thereof, and a blade actuating stem on its other end, a bracket mounted on said base plate, a switch in series with said solenoid carried by said bracket, a resilient blade, one end of which is carried by said bracket and engaging a switch actuating pin, a second adjustably mounted bracket mounted on the base plate for holding the other end of the blade, and a spring for urging the armature toward the blade.

7. In an alarm bell, the combination of a base plate, a solenoid mounted on said base plate and having an armature guided therein for movement axially thereof, a microswitch in series with said solenoid, said switch having an actuating pin, a bracket for supporting said switch on the base plate, a resilient switch actuating blade arranged to actuate said pin, a bracket for supporting one end of ,said blade in close proximity to said switch, a bracket for supporting the other end of said blade, and a threaded stem secured to said armature and having a nut thereon arranged to flex said blade and therewith open the contacts of the microswitch.

8. In an alarm bell, the combination of a base plate, a solenoid mounted on said base plate and having an armature guided therein for the movement axially thereof, a bracket secured to said base plate, a microswitch in series with said solenoid, mounted upon said bracket, said switch having an actuating pin, a resilient switch actuating blade arranged to actuate said pin, said blade being mounted at one end upon said bracket in close proximity to the switch, a second bracket secured to said base plate for supporting the other end of said blade, a threaded stem secured to said armature and having a nut thereon arranged to flex said blade and therewith open the contacts of the microswitch, and a coiled compression spring surrounding said armature and engaging a shoulder thereon.

ARTHUR W. FRUH.

REFERENQES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 235,943 Holcombe Dec. 28, 1880 757,991 Christmas Apr. 19, 1904 1,469,654 Kotzebue Oct, 2, 1923 2,286,176 Boisselier June 9, 1942 1,925,561 Lake Sept. 5, 1932 2,344,523 Stern Mar, 21, 1944 2,357,743 Kenerson September 1944 2,288,938 Claytor July 7, 1942 2,239,312 Berges Apr. 22, 1941 1,157,508 Charland et a1 Oct. 19, 1915 1,199,699 Henderson Sept. 26, 1916 1,797,013 Moran Mar. 17, 1931 1,962,926 Deary June 12, 1934 2,099,929 Ebert Nov. 23, 1937 2,225,558 Edwards Dec. 17, 1940 FOREIGN PATENTS Number Country Date 526,500 Great Britain Sept. 19, 1940 

